The bats (order Chiroptera) usually comprise 40±50% of the mammalian species in tropical habitats, and hence constitute a considerable and important component of the biodiversity. Diversity of neotropical bats is traditionally monitored by mist-netting, as this method is reasonably efficient for detecting gleaning species and other lowintensity echolocators. However, this method is relatively inefficient in the case of aerial insectivores, particularly emballonurids, molossids and most vespertilionids. Aerial insectivores therefore tend to be underrepresented in most bat surveys based on mist-netting. However, because most aerial insectivores forage by using high-intensity echolocation calls, they can be identified and monitored with relative efficiency by acoustic methods. The use of echolocation calls to conduct inventories of insectivorous bats in the Neotropics is hindered at present by a poor knowledge of the details and the variation in the echolocation calls of most species. In the case of aerial insectivorous bats, their ability to fly and their capacity of detection of the mist-net, make almost impossible to asset accurately abundancy and habitat use.

The pourpose of this work was to describe the echolocation calls of insectivorous bats occuring in the Yucatán penninsula using time expanded recording, and to evaluate the possibilities of discrimination among species using 10 call parameters. Bats were captured in different points in the penninsula and 13 species belonging to the families molossidae, mormoopidae, natalidae and vespertilionidae were recorded. Echolocation calls were digitalized and analyzed with the SonoBat software (Sonobat Co. Arcata, CA). Multivariate Discriminan analysis were applied to call parameters of 9 species.

Results/Conclusions

A function based on 5 call parameters duration(ms), Preccallinter(ms), Hifreq(kHz), Lofreq(kHz), and Fmaxampl(kHz) provided a correct overal classification of aproximately 90%. The clasification method show some geographic variability for the call parameters also. Although there were limitations, this approach allows to obtain information about the precense and habitat use of a large amount of species, and provide a closer comprehension of the bat fauna from Yucatan, Mexico.